1. Field of the Invention
The present invention relates to an Organic Light Emitting Display (OLED) with a conductive spacer and its method of manufacture, and more specifically to an OLED with a conductive spacer having power supply stripes respectively formed on an upper and lower substrates being electrically connected to each other by the conductive spacer arranged therebetween.
2. Description of Related Art
Organic Light Emitting Displays (OLEDs) are emissive displays which electrically excite a compound material having a phosphorescence or fluorescence optical property and thereby emits visible light and have been considered to be the next generation display because they can solve the problems concerned with existing Liquid Crystal Displays (LCDs), especially in that OLEDs can be driven with a low voltage, can be easily thin-filmed, have a good viewing-angle range and have a fast response speed, etc.
When an anode and cathode of the OLED are respectively supplied with positive voltages and negative voltages, the holes injected from the anode move into an organic Emitting Film Layer (EML) via a Hole Transport Layer (HTL), whereas the electrons injected from the cathode move into the EML via an Electron Transport Layer (ETL). Then, within the EML, the electrons and the holes are recombined to produce the excitons which in turn make a transition from an excitation state to a base band state, resulting in emitting light to form an image.
In the view of the manufacturing quality of OLED, it is very important to reduce the area of “dead space”, namely, to reduce a non-emissive region in which light emission does not occur, thereby resulting in compact OLEDs. Contrary to the case of the LCD where each pixel need not be supplied with a respective voltage, each pixel must be supplied with the same respective voltage in the case of OLED, especially active matrix OLEDs, thus requiring relatively wider power supply lines to be arranged in the outer region of the active area, namely, the emissive regions, to reduce the voltage drop (I-R drop).
An OLED includes an inner region, representing the emissive region and an outer region excluding the inner region, representing the non-emissive region, in other words, dead space. The power supply stripe is located within the outer region.
The OLED is formed of the combination of an upper substrate and a lower substrate having a thin film transistor. During the combination step, the power supply stripe is formed on the lower substrate in the non-emissive region and then sealed by a sealing portion.
In driving the OLED, the area of the stripe required to maintain the amount of stripe material and length of the stripe for constantly supplying the power within the tolerable voltage drop range is constant. Consequently, if the width of the stripe is reduced to diminish the non-emissive region, then the thickness of the stripe must increase according. In other words, in order to supply the same amount of current when the width of the stripe is reduced and thus the area of the non-emissive region is diminished, the thickness of the stripe must increase.
In order to reduce the non-emissive region of the OLED discussed above, an increase in the thickness of the stripe is needed due to the reduction of the width of the stripe. However, to produce such a construction, the manufacturing process of the OLED is more complicated because the steps of thickly depositing the stripe and partially etching the thickly deposited layer are involved in the process.